"If All the Ice Melted" is the title of the National Geographic's new online interactive segment, and the results are scary.

The new online maps shows the world's land masses as if ice no longer existed at the poles. Sea levels have risen 216 feet, whole habitats are gone, and entire chunks of continents are under water.

If all of the sea-bound ice in the world melted, a number of things would occur. The world's average temperature would increase from 58 to 80 degrees Fahrenheit. In North America alone, huge parts of Mexico, the U.S., and Canada would be under water. The entire eastern seaboard, Florida, and large areas of California and the South would be swimming with the fish.

Europe and the Middle East would lose many of their greatest cities. London, Amsterdam, and St. Petersburg would be gone; Copenhagen, Barcelona, and Cairo would be swallowed up. The rich histories of Alexandria, Baghdad, Istanbul, and Rome would become sites for future underwater archaeological dives.

Asia, Hong Kong, Tokyo, Shanghai, Manila, and Singapore would all be under water as well. Bangkok, Calcutta, and Mumbai, along with lands that are now home to 600 million Chinese people, would disappear. Imagine how many people could be living on those lands 5,000 years from now …

In such a catastrophic alteration to the world's great landmasses scenario, Africa would lose the fewest miles of coast land compared to other continents. But the rising global temperatures would likely make it uninhabitable nonetheless, as Tunis, Tripoli, Cape Town, and Mombasa would become the "new Atlantises."

There are over 5 million cubic miles of ice on Earth. Scientists and the National Geographicnote that it would take 5,000 years for all of the world's ice to melt. Such a long-term event would be most extreme on the spectrum of potential results of global climate change, but if humans continue pushing carbon into the atmosphere, we can theoretically melt all the ice.

The map is a sobering realization that much of humanity has built its civilization close to the sea. If nothing is done to combat global warming, humans and all of mankind is in trouble.